In vitro antioxidant activity and gas chromatographymass spectrometry analysis of solvent extracts of Kigelia africana stem bark
Objective: Kigelia africana is widely used, traditionally, in Africa in the treatment of many conditions and complaints such as kidney and stomach disorders, malaria, wounds, and venereal diseases. In the present study, an attempt has been made to investigate the antioxidant activity of extracted fractions of the stem bark and analyze the non-polar fractions for the presence of various components that may be responsible for their antioxidant properties. Methods: The antioxidant activity was evaluated using 1,1-diphenyl-2-picrylhydrazyl, 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) radical cation and nitric oxide radical scavenging models. Analysis of the chemical components of the solvent extracts was carried out by gas chromatography-mass spectrometry (GC-MS). Results: Strong activity (71-89% inhibition) was found for the ethyl acetate fraction, whereas the non-polar chloroform fraction exhibited a relatively weak activity (24-48%) inhibition, at 25 μg/ml concentration. GC-MS analysis of the non-polar extracted fractions identified 21 and 12 compounds for the hexane and chloroform fractions, respectively, of which α-terpineol (2) (39.21%) was the main component identified for the hexane extract, and α-amyrin (9) (32.54%) was the main component identified for the chloroform extract. Conclusion: This study shows that the non-polar extracted fractions of K. africana stem bark may be a potential source of natural antioxidants or bioactive agents.